La Niņa continued during
January 2009, as negative sea surface temperature (SST) anomalies strengthened
across the central and east-central equatorial
The latest monthly SST index was -1.0°C in the Niņo-3.4 region,
and -0.7°C in the Niņo-4 region (Table T2).
The oceanic thermocline along
the equator, measured by the depth of the 20°C
isotherm, remained shallower than average across the eastern half of the
equatorial Pacific during January in response to anomalously strong oceanic
upwelling (Figs. T15, T16).
Consistent with these conditions, subsurface temperatures in the region reached
4-7oC below average at thermocline depth (Fig. T17).
Enhanced low-level easterly
winds and upper-level westerly winds were present across the equatorial
during January (Figs. T20,
T21). These conditions continued to be associated
with enhanced oceanic upwelling, and also with suppressed convection over the
central equatorial Pacific Ocean and enhanced convection across
This combination of oceanic and atmospheric conditions reflects a continuation
of La Niņa.
the latest status of the ENSO cycle see the ENSO Diagnostic Discussion at: